diff options
| author | Sandipan Das <sandipan.das@amd.com> | 2026-06-01 20:28:46 +0530 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-06-04 11:38:36 +0200 |
| commit | 73a4c02f94a98d94480c3e5c81450215a4da05ba (patch) | |
| tree | fd01dc5e35d4406346520143abe88d0394377bcc | |
| parent | 66cc29745f2f5815482587bb9fbc1e8a3e6fcf00 (diff) | |
perf/x86/amd/core: Always use the NMI latency mitigation
Commit df4d29732fda ("perf/x86/amd: Change/fix NMI latency mitigation
to use a timestamp") fixed handling of late-arriving NMIs but limited
the mitigation to processors having X86_FEATURE_PERFCTR_CORE. However,
it is unclear if processors without this feature are also affected.
When Mediated vPMU is enabled on affected hardware, it is also possible
to bypass the fix inside KVM guests if X86_FEATURE_PERFCTR_CORE is
removed from the guest CPUID (e.g. using "-cpu host,-perfctr-core" with
QEMU). Hence, use the mitigation at all times.
Fixes: df4d29732fda ("perf/x86/amd: Change/fix NMI latency mitigation to use a timestamp")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/29a3c970da289ab8f24282933bdb36545c0403e8.1780325517.git.sandipan.das@amd.com
| -rw-r--r-- | arch/x86/events/amd/core.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index 0c92ed5f464b..abc84a92cd59 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -1412,12 +1412,12 @@ static int __init amd_core_pmu_init(void) u64 even_ctr_mask = 0ULL; int i; - if (!boot_cpu_has(X86_FEATURE_PERFCTR_CORE)) - return 0; - /* Avoid calculating the value each time in the NMI handler */ perf_nmi_window = msecs_to_jiffies(100); + if (!boot_cpu_has(X86_FEATURE_PERFCTR_CORE)) + return 0; + /* * If core performance counter extensions exists, we must use * MSR_F15H_PERF_CTL/MSR_F15H_PERF_CTR msrs. See also |